硝酸肼体系中U(Ⅵ)电解还原制备U(Ⅳ)工艺研究

Study on Electrolytic Reduction of U(Ⅵ) to U(Ⅳ) in Hydrazine Nitrate Media

乏燃料后处理PUREX流程中铀钚分离主要是采用四价铀U(Ⅳ)作为还原剂将有机相中的四价钚Pu(Ⅳ)还原为三价钚Pu(Ⅲ)进入水相,而六价铀U(Ⅵ)仍保留在有机相中,从而实现铀钚分离。电解还原法是目前制备U(Ⅳ)的主要工艺。在新型电解槽中探究了硝酸铀酰料液在电解槽中的停留时间、料液循环形式、阴阳极板面积比和电源布置方式对电解槽出口U(Ⅳ)质量浓度的影响,获得了各因素对电解还原性能的影响规律,并进行了1∶1规模连续运行验证试验,为U(Ⅵ)电解还原在工程中的应用提供了重要的参考依据。

The separation of uranium and plutonium in the PUREX process of the spent fuel reprocessing mainly uses tetravalent(U(Ⅳ)) as a reducing agent to reduce the tetravalent plutonium(Pu(Ⅳ)) in the organic phase to trivalent plutonium(Pu(Ⅲ)). Trivalent plutonium enters the water phase, and hexavalent uranium(U(Ⅵ)) remains in the organic phase, thus realizing the separation of uranium and plutonium. The electrolytic reduction method is currently the main process for the preparation of U(Ⅳ). In this paper, the influence of the residence time of the uranium nitrate in the electrolytic cell, the circulation of the feed liquid, the area ratio of the cathode and anode plates and the layout of power on the mass concentration of U(Ⅳ) was investigated, the effect law of each factor on the electrolytic reduction performance was obtained, and continuous test in 1∶1 scale-electrolytic cell was carried out, which could provide important reference for the application of electrolytic reduction of U(Ⅵ) in engineering.